Does the "mod" you refer too, replace SW-3 with a multi wafer assembly?
I ask because according to the schematic and the picture in the manual I have, SW-3 is only a 2 position switch, AM/CW, with terminals on only one side.
In the schematic, Pole "A" Applies B+ to the modulator plates, Pole "B" shorts out the modulation transformer secondary in "CW", and Pole "C" switches the Oscillator Cathode to the Key jack. I don't see any mention of a "D".
There seem to be a few "Conventions" regarding the callout of wafers, terminals, and sections of wafer switches.
One, numbers the switch sections A, B, C, etc with each side of each wafer being denoted by a letter, with "A" being the front side of the wafer closest to the front panel, while the rear side of that wafer is "B", the next wafer being "C" and "D", and so on.
Another scheme is to number the individual wafers 1, 2, 3, etc, with "!" being closest to the front panel, then call out "F" for the front side, and "R" for the rear side.
In this case of SW-3 having only 2 to positions, each "Pole" is numbered, in the schematic, as "A", "B", "C", and "D", and I don't see "D" being used. Switches with as many as 4 poles can be implemented on one side of a wafer, depending on how many positions are needed per pole.
Sometimes, though apparently not in this case, there will be a note defining the position of the switches as shown in the schematic.
As for wires of differing color, or added wires, I would think a little time with a VOM would clear up those issues.